<p>表：<code>students</code></p>

<pre>
+--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| student_id   | int     |
| student_name | varchar |
| major        | varchar |
+--------------+---------+
student_id 是这张表的唯一主键。
每一行包含有关学生及其学术专业的信息。
</pre>

<p>表：<code>study_sessions</code></p>

<pre>
+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| session_id    | int     |
| student_id    | int     |
| subject       | varchar |
| session_date  | date    |
| hours_studied | decimal |
+---------------+---------+
session_id 是这张表的唯一主键。
每一行代表一个学生针对特定学科的学习时段。
</pre>

<p>编写一个解决方案来找出遵循 <strong>螺旋学习模式</strong> 的学生——即那些持续学习多个学科并按循环周期进行学习的学生。</p>

<ul>
	<li>螺旋学习模式意味着学生以重复的顺序学习至少 <code>3</code> 个 <strong>不同的学科</strong>。</li>
	<li>模式必须重复 <strong>至少</strong><strong>&nbsp;</strong><code>2</code><strong>&nbsp;个完整周期</strong>（最少&nbsp;<code>6</code>&nbsp;次学习记录）。</li>
	<li>两次学习记录必须是间隔不超过&nbsp;<code>2</code>&nbsp;天的 <strong>连续日期</strong>。</li>
	<li>计算 <strong>循环长度</strong>（模式中不同的学科数量）。</li>
	<li>计算模式中所有学习记录的 <strong>总学习时长</strong>。</li>
	<li>仅包含循环长度 <strong>至少为&nbsp;</strong><strong>&nbsp;</strong><code>3</code><strong>&nbsp;门学科</strong>&nbsp;的学生。</li>
</ul>

<p>返回结果表按循环长度 <strong>降序</strong>&nbsp;排序，然后按总学习时间 <strong>降序</strong>&nbsp;排序。</p>

<p>结果格式如下所示。</p>

<p>&nbsp;</p>

<p><strong class="example">示例：</strong></p>

<div class="example-block">
<p><strong>输入：</strong></p>

<p>students 表：</p>

<pre class="example-io">
+------------+--------------+------------------+
| student_id | student_name | major            |
+------------+--------------+------------------+
| 1          | Alice Chen   | Computer Science |
| 2          | Bob Johnson  | Mathematics      |
| 3          | Carol Davis  | Physics          |
| 4          | David Wilson | Chemistry        |
| 5          | Emma Brown   | Biology          |
+------------+--------------+------------------+
</pre>

<p>study_sessions 表：</p>

<pre class="example-io">
+------------+------------+------------+--------------+---------------+
| session_id | student_id | subject    | session_date | hours_studied |
+------------+------------+------------+--------------+---------------+
| 1          | 1          | Math       | 2023-10-01   | 2.5           |
| 2          | 1          | Physics    | 2023-10-02   | 3.0           |
| 3          | 1          | Chemistry  | 2023-10-03   | 2.0           |
| 4          | 1          | Math       | 2023-10-04   | 2.5           |
| 5          | 1          | Physics    | 2023-10-05   | 3.0           |
| 6          | 1          | Chemistry  | 2023-10-06   | 2.0           |
| 7          | 2          | Algebra    | 2023-10-01   | 4.0           |
| 8          | 2          | Calculus   | 2023-10-02   | 3.5           |
| 9          | 2          | Statistics | 2023-10-03   | 2.5           |
| 10         | 2          | Geometry   | 2023-10-04   | 3.0           |
| 11         | 2          | Algebra    | 2023-10-05   | 4.0           |
| 12         | 2          | Calculus   | 2023-10-06   | 3.5           |
| 13         | 2          | Statistics | 2023-10-07   | 2.5           |
| 14         | 2          | Geometry   | 2023-10-08   | 3.0           |
| 15         | 3          | Biology    | 2023-10-01   | 2.0           |
| 16         | 3          | Chemistry  | 2023-10-02   | 2.5           |
| 17         | 3          | Biology    | 2023-10-03   | 2.0           |
| 18         | 3          | Chemistry  | 2023-10-04   | 2.5           |
| 19         | 4          | Organic    | 2023-10-01   | 3.0           |
| 20         | 4          | Physical   | 2023-10-05   | 2.5           |
+------------+------------+------------+--------------+---------------+
</pre>

<p><strong>输出：</strong></p>

<pre class="example-io">
+------------+--------------+------------------+--------------+-------------------+
| student_id | student_name | major            | cycle_length | total_study_hours |
+------------+--------------+------------------+--------------+-------------------+
| 2          | Bob Johnson  | Mathematics      | 4            | 26.0              |
| 1          | Alice Chen   | Computer Science | 3            | 15.0              |
+------------+--------------+------------------+--------------+-------------------+
</pre>

<p><strong>解释：</strong></p>

<ul>
	<li><strong>Alice Chen (student_id = 1):</strong>

	<ul>
		<li>学习序列：Math → Physics → Chemistry → Math → Physics → Chemistry</li>
		<li>模式：3 门学科（Math，Physics，Chemistry）重复 2 个完整周期</li>
		<li>连续日期：十月 1-6，没有超过 2 天的间隔</li>
		<li>循环长度：3 门学科</li>
		<li>总时间：2.5 + 3.0 + 2.0 + 2.5 + 3.0 + 2.0 = 15.0 小时</li>
	</ul>
	</li>
	<li><strong>Bob Johnson (student_id = 2):</strong>
	<ul>
		<li>学习序列：Algebra → Calculus → Statistics → Geometry → Algebra → Calculus → Statistics → Geometry</li>
		<li>模式：4 门学科（Algebra，Calculus，Statistics，Geometry）重复 2 个完整周期</li>
		<li>连续日期：十月 1-8，没有超过 2 天的间隔</li>
		<li>循环长度：4 门学科</li>
		<li>总时间：4.0 + 3.5 + 2.5 + 3.0 + 4.0 + 3.5 + 2.5 + 3.0 = 26.0&nbsp;小时</li>
	</ul>
	</li>
	<li><strong>未包含学生：</strong>
	<ul>
		<li>Carol Davis (student_id = 3)：仅 2 门学科（生物，化学）- 未满足至少 3 门学科的要求</li>
		<li>David Wilson (student_id = 4)：仅 2 次学习课程，间隔 4 天 - 不符合连续日期要求</li>
		<li>Emma Brown (student_id = 5)：没有记录学习课程</li>
	</ul>
	</li>
</ul>

<p>结果表以 cycle_length 降序排序，然后以 total_study_hours 降序排序。</p>
</div>
